The UK jobs market is "skating on thin ice", with cracks starting to appear in many areas of the economy, says a new report.
Employment group Manpower said that on the surface, the EU referendum had done little to dampen firms' immediate recruitment plans.
A survey of over 2,100 employers showed there was no "Brexit backlash", but ManpowerGroup warned that this could be the calm before the storm.
"Conducted in the weeks following the referendum, the survey shows that while UK job prospects have held firm, cracks in the ice are appearing with six out of nine sectors surveyed reporting a fall in jobs optimism," said the report.
Mark Cahill, ManpowerGroup UK managing director said: "After the initial shock of Brexit, we're entering a new phase of prolonged economic uncertainty. The future of freedom of movement across the EU is of particular concern.
"As UK businesses are reliant on European talent to help fill the skills gap, we urge the Government to prioritise maintaining the free movement of people across the EU during its negotiations.
"This would make sure the UK remains competitive, while sending a powerful message to skilled jobseekers - Britain remains open for business."
The report said the biggest cause for concern on the jobs front was in business and financial services, construction and utilities, while prospects also fell in manufacturing.
Manpower said there had been an 800% increase in applications for finance positions in Dublin since the EU referendum.
The study also found that job prospects in the public sector had fallen to the weakest level in four years.